Cutaneous and visceral leishmaniasis occur in undetermined degrees of prevalence in different parts of Ethiopia. Epidemiological and immunological studies of localized and diffuse cutaneous leishmaniasis during the past six years have revealed that the differences between the two types are due to host immunological response variations rather than differences in the etiologic agents. Future studies will involve conclusive determination of suspected vector(s), reservoir host(s), and transmission sites of the disease. There is very little known about visceral leishmaniasis (kala-azar) as it occurs in Ethiopia. The epidemiology (including vectors and reservoir hosts), pathology, and immunology of this disease will be studied. Speculations based on studies done in the Sudan, Kenya and other parts of the world lead us to believe that the Ethiopian variety of kala-azar, as in the case of oriental sore, may have unique epidemiological and immunological patterns. The experimental methods to be followed will be essentially those reported previously. Epidemiological studies on kala-azar will be conducted in known endemic areas, including Setit Humera (northwestern Ethiopia extending to the Red Sea), and Gemu Gofa (southwestern, Ethio-Kenyan border). These are all important public health and agricultural development areas; the study will therefore have a direct and immediate use for Ethiopia.